1. Field of the Invention
The present invention relates to a substrate processing apparatus which sequentially transports thin plate-like precision electronic substrates such as semiconductor wafers, glass substrates for liquid crystal display devices and substrates for solar cells (hereinafter referred to simply as “substrates”) to perform a cleaning process and the like on the substrates.
2. Description of the Background Art
As is well known, semiconductor and liquid crystal display products and the like are fabricated by performing a series of processes including cleaning, resist coating, exposure, development, etching, interlayer insulation film formation, heat treatment, dicing and the like on the aforementioned substrates. A scrub cleaning process which brings a brush into contact with or into proximity to a main surface of a rotating substrate to mechanically remove deposits from the main surface of the substrate is known as one of the processes of cleaning substrates. A substrate processing apparatus which performs such a scrub cleaning process is disclosed in U.S. Patent Application Publication No. 2008/0156351.
In the substrate processing apparatus disclosed in U.S. Patent Application Publication No. 2008/0156351, an indexer block which accumulates unprocessed substrates and processed substrates therein and a processing block which performs the scrub cleaning process on the substrates are provided in juxtaposition. In general, the scrub cleaning process is performed on not only the front surface of a substrate but also the back surface thereof. The processing block disclosed in U.S. Patent Application Publication No. 2008/0156351 carries front surface cleaning units and back surface cleaning units. In the back surface cleaning units, the process is performed on a substrate with a back surface positioned to face upward. This necessitates a mechanism for inverting or flipping a substrate in the substrate processing apparatus which performs the back surface cleaning.
In the substrate processing apparatus disclosed in U.S. Patent Application Publication No. 2008/0156351, inverting units (referred to as “reversing units” in this publication) are provided as a substrate passing part at a connecting portion of the indexer block and the processing block. In other words, the substrate passing part present between the indexer block and the processing block to pass substrates therebetween also functions as the inverting units. This reduces the transporting steps in the apparatus disclosed in U.S. Patent Application Publication No. 2008/0156351 to improve the throughput for substrate processing.
However, the provision of an inverting unit for inverting a substrate and the step of inverting the substrate 180 degrees by means of the inverting unit are essential for the background art techniques including U.S. Patent Application Publication No. 2008/0156351. Accordingly, the time to perform this step is required for the background art techniques. For this reason, there is a limit on the shortening of the time required until a substrate is transported into the back surface cleaning unit. In particular, the 180-degree inversion of large-diameter semiconductor wafers having a diameter of 450 mm whose future developments are being contemplated requires longer time than that of conventional semiconductor wafers (having a diameter of 300 mm or less). Thus, there is a danger that throughput decreases for such large-diameter semiconductor wafers.
An inverting unit for inverting large-diameter semiconductor wafers is accordingly large in size to present another problem in the increase in the size of the substrate processing apparatus.